Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling

Seyed Mojtaba Ghiasi; Tina Dahlby; Caroline Hede Andersen; Leena Haataja; Sólrun Petersen; Muhmmad Omar-Hmeadi; Mingyu Yang; Celina Pihl; Sophie Emilie Bresson; Muhammad Saad Khilji; Kristian Klindt; Oana Cheta; Marcelo J Perone; Björn Tyrberg; Clara Prats; Sebastian Barg; Anders Tengholm; Peter Arvan; Thomas Mandrup-Poulsen; Michal Tomasz Marzec

doi:10.2337/db18-0671

Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling

Seyed Mojtaba Ghiasi, Tina Dahlby, Caroline Hede Andersen, Leena Haataja, Sólrun Petersen, Muhmmad Omar-Hmeadi, Mingyu Yang, Celina Pihl, Sophie Emilie Bresson, Muhammad Saad Khilji, Kristian Klindt, Oana Cheta, Marcelo J Perone, Björn Tyrberg, Clara Prats, Sebastian Barg, Anders Tengholm, Peter Arvan, Thomas Mandrup-Poulsen, Michal Tomasz Marzec

17 Citations (Scopus)

Abstract

Although endoplasmic reticulum (ER) chaperone binding to mutant proinsulin has been reported, the role of protein chaperones in the handling of wild-type proinsulin is underinvestigated. Here, we have explored the importance of glucose-regulated protein 94 (GRP94), a prominent ER chaperone known to fold insulin-like growth factors, in proinsulin handling within b-cells. We found that GRP94 coimmunoprecipitated with proinsulin and that inhibition of GRP94 function and/or expression reduced glucose-dependent insulin secretion, shortened proinsulin half-life, and lowered intracellular proinsulin and insulin levels. This phenotype was accompanied by post-ER proinsulin misprocessing and higher numbers of enlarged insulin granules that contained amorphic material with reduced immunogold staining for mature insulin. Insulin granule exocytosis was accelerated twofold, but the secreted insulin had diminished bioactivity. Moreover, GRP94 knockdown or knockout in b-cells selectively activated protein kinase R–like endoplasmic reticulum kinase (PERK), without increasing apoptosis levels. Finally, GRP94 mRNA was overexpressed in islets from patients with type 2 diabetes. We conclude that GRP94 is a chaperone crucial for proinsulin handling and insulin secretion.

Original language	English
Journal	Diabetes
Volume	68
Issue number	4
Pages (from-to)	747-760
Number of pages	14
ISSN	0012-1797
DOIs	https://doi.org/10.2337/db18-0671
Publication status	Published - 1 Apr 2019

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Ghiasi, S. M., Dahlby, T., Hede Andersen, C., Haataja, L., Petersen, S., Omar-Hmeadi, M., Yang, M., Pihl, C., Bresson, S. E., Khilji, M. S., Klindt, K., Cheta, O., Perone, M. J., Tyrberg, B., Prats, C., Barg, S., Tengholm, A., Arvan, P., Mandrup-Poulsen, T., & Marzec, M. T. (2019). Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling. Diabetes, 68(4), 747-760. https://doi.org/10.2337/db18-0671

Ghiasi, SM, Dahlby, T, Hede Andersen, C, Haataja, L, Petersen, S, Omar-Hmeadi, M, Yang, M, Pihl, C, Bresson, SE, Khilji, MS, Klindt, K, Cheta, O, Perone, MJ, Tyrberg, B, Prats, C, Barg, S, Tengholm, A, Arvan, P, Mandrup-Poulsen, T & Marzec, MT 2019, 'Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling', Diabetes, vol. 68, no. 4, pp. 747-760. https://doi.org/10.2337/db18-0671

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title = "Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling",

abstract = "Although endoplasmic reticulum (ER) chaperone binding to mutant proinsulin has been reported, the role of protein chaperones in the handling of wild-type proinsulin is underinvestigated. Here, we have explored the importance of glucose-regulated protein 94 (GRP94), a prominent ER chaperone known to fold insulin-like growth factors, in proinsulin handling within b-cells. We found that GRP94 coimmunoprecipitated with proinsulin and that inhibition of GRP94 function and/or expression reduced glucose-dependent insulin secretion, shortened proinsulin half-life, and lowered intracellular proinsulin and insulin levels. This phenotype was accompanied by post-ER proinsulin misprocessing and higher numbers of enlarged insulin granules that contained amorphic material with reduced immunogold staining for mature insulin. Insulin granule exocytosis was accelerated twofold, but the secreted insulin had diminished bioactivity. Moreover, GRP94 knockdown or knockout in b-cells selectively activated protein kinase R–like endoplasmic reticulum kinase (PERK), without increasing apoptosis levels. Finally, GRP94 mRNA was overexpressed in islets from patients with type 2 diabetes. We conclude that GRP94 is a chaperone crucial for proinsulin handling and insulin secretion.",

author = "Ghiasi, {Seyed Mojtaba} and Tina Dahlby and {Hede Andersen}, Caroline and Leena Haataja and S{\'o}lrun Petersen and Muhmmad Omar-Hmeadi and Mingyu Yang and Celina Pihl and Bresson, {Sophie Emilie} and Khilji, {Muhammad Saad} and Kristian Klindt and Oana Cheta and Perone, {Marcelo J} and Bj{\"o}rn Tyrberg and Clara Prats and Sebastian Barg and Anders Tengholm and Peter Arvan and Thomas Mandrup-Poulsen and Marzec, {Michal Tomasz}",

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T1 - Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling

AU - Ghiasi, Seyed Mojtaba

AU - Dahlby, Tina

AU - Hede Andersen, Caroline

AU - Haataja, Leena

AU - Petersen, Sólrun

AU - Omar-Hmeadi, Muhmmad

AU - Yang, Mingyu

AU - Pihl, Celina

AU - Bresson, Sophie Emilie

AU - Khilji, Muhammad Saad

AU - Klindt, Kristian

AU - Cheta, Oana

AU - Perone, Marcelo J

AU - Tyrberg, Björn

AU - Prats, Clara

AU - Barg, Sebastian

AU - Tengholm, Anders

AU - Arvan, Peter

AU - Mandrup-Poulsen, Thomas

AU - Marzec, Michal Tomasz

PY - 2019/4/1

Y1 - 2019/4/1

N2 - Although endoplasmic reticulum (ER) chaperone binding to mutant proinsulin has been reported, the role of protein chaperones in the handling of wild-type proinsulin is underinvestigated. Here, we have explored the importance of glucose-regulated protein 94 (GRP94), a prominent ER chaperone known to fold insulin-like growth factors, in proinsulin handling within b-cells. We found that GRP94 coimmunoprecipitated with proinsulin and that inhibition of GRP94 function and/or expression reduced glucose-dependent insulin secretion, shortened proinsulin half-life, and lowered intracellular proinsulin and insulin levels. This phenotype was accompanied by post-ER proinsulin misprocessing and higher numbers of enlarged insulin granules that contained amorphic material with reduced immunogold staining for mature insulin. Insulin granule exocytosis was accelerated twofold, but the secreted insulin had diminished bioactivity. Moreover, GRP94 knockdown or knockout in b-cells selectively activated protein kinase R–like endoplasmic reticulum kinase (PERK), without increasing apoptosis levels. Finally, GRP94 mRNA was overexpressed in islets from patients with type 2 diabetes. We conclude that GRP94 is a chaperone crucial for proinsulin handling and insulin secretion.

AB - Although endoplasmic reticulum (ER) chaperone binding to mutant proinsulin has been reported, the role of protein chaperones in the handling of wild-type proinsulin is underinvestigated. Here, we have explored the importance of glucose-regulated protein 94 (GRP94), a prominent ER chaperone known to fold insulin-like growth factors, in proinsulin handling within b-cells. We found that GRP94 coimmunoprecipitated with proinsulin and that inhibition of GRP94 function and/or expression reduced glucose-dependent insulin secretion, shortened proinsulin half-life, and lowered intracellular proinsulin and insulin levels. This phenotype was accompanied by post-ER proinsulin misprocessing and higher numbers of enlarged insulin granules that contained amorphic material with reduced immunogold staining for mature insulin. Insulin granule exocytosis was accelerated twofold, but the secreted insulin had diminished bioactivity. Moreover, GRP94 knockdown or knockout in b-cells selectively activated protein kinase R–like endoplasmic reticulum kinase (PERK), without increasing apoptosis levels. Finally, GRP94 mRNA was overexpressed in islets from patients with type 2 diabetes. We conclude that GRP94 is a chaperone crucial for proinsulin handling and insulin secretion.

U2 - 10.2337/db18-0671

DO - 10.2337/db18-0671

M3 - Journal article

C2 - 30670477

SN - 0012-1797

VL - 68

SP - 747

EP - 760

JO - Diabetes

JF - Diabetes

IS - 4

ER -

Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 Is Essential for Proinsulin Handling

Abstract

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